We are interested in the form and evolution of the entanglement entropy in an
expanding background. Our motivation comes from the wish to understand its
possible role in early-time cosmology. For this purpose, we must consider
time-dependent backgrounds, such as the Friedmann-Lemaitre-Robertson-Walker
(FLRW) universe.
Also, the de Sitter (dS) spacetime in flat slicing is of interest as the relevant
background for inflation.
The holographic entanglement entropy can be computed in such cases
through a generalization of the Ryu-Takayanagi proposal for a static background [1]}.
Several studies of the entanglement entropy on curved backgrounds
have been performed, in which
the connection with the dS gravitational entropy has also been examined [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}.
